In the semiconductor production, the semiconductor heat treatment equipment is an important processing equipment for manufacturing integrated circuits, and is required to have excellent precision and good stability in temperature controlling. During the semiconductor heat treatment, those processes which are susceptible to temperature include oxidation, nitrogenization, dopants diffusion, high temperature anneal, sputter deposition, and plasma treatment. Thus, the temperature has a non-negligible significant influence on the heat treatment effect to the silicon wafer.
For example, a vertical diffusion or oxidation furnace is one of the important semiconductor heat treatment equipment used in the front-end process of the integrated circuit production line. The semiconductor heat treatment equipment mainly consists of a furnace outer shell, an insulation layer, heating units, a reaction tube disposed in the furnace, a boat carrying a plurality of silicon wafers, and an insulation barrel. By keeping a suitable and stable temperature within the reaction tube, a film with good uniformity can be formed on the silicon wafer surface. However, if the temperature in the tube is varied rapidly, the film formed on the silicon wafer surface will not be uniform, which causes lower utilization of the silicon wafer. Therefore, during the heat treatment process, the temperature in the reaction tube must be kept stable and meet the required temperature of the process.
In order to measure the temperature in the reaction tube, the thermocouple is utilized as a temperature measuring device. The thermocouple is generally wrapped by a quartz cover due to the high temperature inside the tube. Since the quartz cover of the thermocouple is fragile, the fixation of the quartz cover is difficult and generally needs a fixing device. However, the thermocouple fixing device is hard to install inside the tube due to the higher cleanliness requirement for the process. Thus, the thermocouple fixing device can only be installed outside the reaction tube by extending one end of the thermocouple into the tube and fixing the other end outside the tube through a support or other simple structures.
During the usage of the conventional thermocouple fixing device, there are some disadvantages as follows, which can be understood by those skilled in the art:
1. Since the other end of the thermocouple cannot be stably fixed, the thermocouple can easily move along the length direction, thereby shifting the measurement position of the thermocouple from the designated position and causing inaccurate measured temperature.
2. Since the quartz cover is generally circular, the thermocouple can be easily rotated along the circumference, thereby also shifting the measurement position of the thermocouple from the designated position, causing measurement error and influencing the process effect.
These two disadvantages mentioned above may cause temperature error during the temperature measurement by the thermocouple in the tube, which further affects the reliability of the heat treatment of the silica wafer, the production efficiency and cost. Therefore, a thermocouple fixing device that can locate and fix the thermocouple in an accurate position within the tube need to be provided to ensure an accurate temperature measurement result of the thermocouple.